A deposit of the material set out herein has been deposited in American Type Culture Collection No. ATCC 55084, 55083, 55081.
1. Field of the Invention
This invention relates to a new process for biotechnological upgrading of raw shale oil. More particularly, the invention relates to a new biotechnological process for treating raw shale oil to remove the nitrogen-containing contaminants thereof.
Specifically, the invention provides a new technique using microbial cultures to selectively remove damaging nitrogen-containing compounds, such as, for example, the aliphatic and heterocyclic nitrogen compounds as nitriles, quinolines and the like, from raw shale oil without attacking the valuable hydrocarbons in the said oil. The new process broadly comprises treating the raw shale oil with special microbial cultures having specific ability to degrade the harmful nitrogen-containing compounds, such as the amines, nitriles and heterocylics as the quinolines and pyridines, and converting them into non damaging components, without degrading any of the valuable hydrocarbons contained in said oil, said treatment being accomplished in the presence of an alternative source of carbon, such as glucose or succinate under aerobic conditions.
The invention further provides a technique for the preparation of microbal populations which are specific to the degradation of the aliphatic and heterocyclic nitrogen-containing compounds generally found in the raw shale oil.
2. Prior Art
World wide demand for hydrocarbons and related products is continuing at a high annual rate. Crude petroleum and natural gas are basic in satisfying these demands but shortages can be forseen in the near future even though new oil and gas resources are being discovered. Therefore, alternate sources and feed stocks, such as coal, tar sands, oil shale and solid crudes are receiving greater consideration.
Oil shales found in large quantities in various locations throughout the world are an ideal source for obtaining additional quantities of hydrocarbons and related products. Oil shales consists of compacted sedimentary inorganic rock particles, generally laminated and partly or entirely encased with a high molecular weight organic solid material called kerogen, which is generally present in amounts of about 6 to 30 percent by weight of the shale. Kerogen is derived from aquatic organisms or waxy spores and pollen grains, comprising hydrocarbons and complex organic-nitrogen, oxygen and sulfur compounds.
Oils produced from the crude oil shales are unlike oil from petroleum reservoirs in having much higher concentrations of the nitrogen and sulfur compounds. The nitrogen content, for example, varies from about 0.5 to 2% which is much higher than the amount in crude oil (about 0.094%).
Because of the excessive amounts of nitrogen and sulfur compounds in the oils obtained by retorting of shales, such oils are unsuited for direct refining into useful fuels. It has been found, for example, that the nitrogen-containing compounds act as poison for the refining catalysts and together with the oxygen compounds cause poor stability of the shale oils.
Attempts have been made in the past to upgrade the shale oils by using modified refinery techniques, particularly by thermal means using molecular hydrogen. High intensity hydrotreatments are very costly and low intensity hydrotreatments have not been entirely satisfactory as they have generally resulted in a low conversion to the desired higher molecular weight products and the desired liquid products have been of low quality in that they may still contain considerable amounts of nitrogen, sulfur and oxygen contaminates.
Although efforts have been made to treat refined oils produced from petroleum to reduce the relatively low concentrations of nitrogen-containing compounds microorganisms and biotechnological processes have not been previously reported for removal of nitrogen from shale oils. Also, previous reports of microbial attack of nitrogen-containing compounds in fuels have not demonstrated selective removal so that hydrocarbons were also degraded. For example, U.S. Pat. No. 3,069,325, which discloses a method for treatment of jet fuels with strains of microorganisms obtained from sea water in the absence of nutrients reported reduction of the nitrogen content from 0.02 to 0.002% relied upon hydrocarbon degrading microorganisms. This process reduced the value of the fuel by removing the valuable hydrocarbons.
It is an object of the invention, therefore, to provide a new process for the treatment of raw shale oil itself to effect a degradation of the damaging nitrogen-containing components. It is a further object to provide a new process for the treatment of raw shale oil to remove the nitrogen-containing contaminants without degrading the important hydrocarbon components. It is a further object to provide a biotechnological method for treating raw shale oil to remove contaminating materials. It is a further object to provide a new process for treating raw shale oil to remove the aliphatic nitrogen-containing compounds, such as the aliphatic amines and nitriles. It is a further object to provide a process for treating raw shale oil to remove the heterocyclic nitrogen compounds such as the quinolines, pyridines and the like. These and other objects will be apparent from the following detailed description thereof.